The present invention relates to a method and an apparatus for photographing an image, and more particularly to a method of and an apparatus for photographing an image displayed on a CRT monitor on a photosensitive medium such as a photographic film by positioning the photosensitive medium, then feeding the photosensitive medium by a certain amount, positioning the CRT monitor in a reference position with respect to each photosensitive medium, and thereafter displacing the CRT monitor in a direction substantially at a right angle to the direction in which the photosensitive medium is fed, while photographing the CRT monitor image on the photosensitive medium, so that the position where images start to be photographed on a plurality of photosensitive mediums is kept constant at all times for increased image quality, and the position for starting to photograph images is stabilized for photographing images accurately.
There have widely been used in recent years image processing systems in which image information created by computerized tomograpy (CT) is displayed on a CRT monitor and photographed on a photographic photosensitive medium by an image photographing apparatus. The image processing system includes the image photographing apparatus, an image input unit such as a medical diagnostic unit, an image information processing unit for processing image information from the image input unit to produce an image to be displayed on the CRT monitor, and an automatic image developing unit for developing photographed images on the photosensitive medium.
In the image photographing apparatus, the photosensitive medium such as a photographic film supplied from a supply magazine is exposed to a plurality of images displayed on the CRT monitor. Various such image photographing apparatus have been proposed thus far. One of the proposed apparatus is disclosed in Japanese Laid-Open Patent Publication No. 61-284749, for example. In the disclosed image photographing apparatus, a photographic film supplied from a supply magazine is fed to an image focusing station by a feed mechanism, and then fixed in position in the image focusing station by a film presser plate which can be displaced perpendicularly toward and away from the film.
Image information displayed on the CRT monitor is imaged or photographed on the film in a certain area thereon by an image-focusing optical mechanism that comprises an image-focusing lens and a light source, or the CRT monitor, which carries the image information. A plurality of different pieces of image information are successively formed on the single photographic film. The image focusing optical mechanism is displaceable two-dimensionally along two axes in order to photograph the images on the film at various locations thereon.
The film on which the pieces of image information have been photographed is then released from the film presser plate by lowering the film presser plate away from the film, and is thereafter delivered by the feed mechanism. The film is fed into a receiver magazine disposed substantially horizontally below the supply magazine, and the receiver magazine is supplied to the automatic image developing unit. The film may directly be fed to the automatic image developing unit.
The image-forming or focusing optical mechanism in the image photographing apparatus can be moved a prescribed interval by a stepping motor or the like and stopped in alignment with an area on the film where an image is to be photographed. The image-focusing optical mechanism is positioned in a reference position only when the image photographing apparatus is energized, and then moved from the reference position in increments by the stepping motor for photographing the images on the film in successive positions thereon. If an error is produced when positioning the optical mechanism in the reference position, or if the optical mechanism is stopped in a misaligned position due for example to erroneous operation of the stepping motor, images will be photographed on all subsequent films in different positions thereon. When this trouble occurs, the images are photographed in improperly displaced positions on the films, and sometimes the images of these films may not be used.
The image photographing apparatus should be equipped with a driver mechanism for angularly moving the film-positioning film presser plate toward and away from the film. Since a plurality of pieces of desired image information are photographed on a single film, the image-focusing optical mechanism is displaceable along two axes, as described above. To effect such two-dimensional displacement of the optical mechanism, the image photographing apparatus is also required to have driver mechanisms for moving the optical mechanism along the respective axes and means for stopping the optical mechanism accurately along the respective axes. Consequently, the image photographing apparatus is considerably complex in structure, large in size, and highly costly to manufacture.
There have been devised various apparatus in which a CRT monitor is movable along one axis and images of different sizes can be photographed. Such apparatus are disclosed in Japanese Laid-Open Patent Publications Nos. 55-60937 and 55-60971, for example. Each of the disclosed apparatus includes a plurality of first image-forming focusing lenses for forming images of smaller sizes and a plurality of second image forming focusing lenses for forming images of larger sizes, the first and second focusing lenses being disposed above a CRT monitor which can be moved in a direction substantially at a right angle to the direction in which photographic films are fed. The first and second focusing lenses are arrayed in the direction of movement of the CRT monitor. The CRT monitor has an optical axis positioned intermediate between the first and second lenses. Therefore, when the first and second focusing lenses are used to photograph displayed images on the CRT monitor, light from the CRT monitor reaches the film at different position along the film feeding direction. Consequently, dependent on whether the first focusing lenses or the second focusing lenses are used, it is necessary to stop the film in a different position where an image is formed, and hence the apparatus is required to have positioning control means or the like for positioning the film.
Moreover, as described above, the plural first and second focusing lenses have to be provided. Therefore, a light-shielding member is needed to prevent light from the CRT monitor from passing through those focusing lenses which are not in use. As a result, the apparatus is quite complex in structure, and the cost of manufacture of the apparatus is high.